Please don't waste your time trying to change the parts. They are not easily second sourced. Buy them from Borbely. They will be relatively expensive, but you are in no position to find them much cheaper. In fact, just get a 'kit' from Borbely, and don't waste your time trying to make it on the cheap. You will pay more, in the long run.

Originally posted by john curl Please don't waste your time trying to change the parts. They are not easily second sourced. Buy them from Borbely. They will be relatively expensive, but you are in no position to find them much cheaper. In fact, just get a 'kit' from Borbely, and don't waste your time trying to make it on the cheap. You will pay more, in the long run.

Why would it be so hard to find them cheaper? Borbely is anything from twice to 5 times the price of other sources.

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UrSv
Those who say it can't be done should not stop those who are doing it.

AlexO, I did not note previously, that you live in Moscow. I understand now that the cost of these components is very high, especially from Erno, with the rate-of-exchange. I was trying to save others, who might live in Germany or many other places in Western Europe, to not waste their time trying to save a few Euros, but I will tell you the whole situation, in order to help you further.
We have used these devices, that Erno Borbely designs with, and sells, for many years. Once, I had 3000 2SJ79's in my possession along with the complement, the 2SK 216 (I think) . They were burned up in a firestorm, but if I had them today, I could sell them and buy a Porsche with the money. What used to cost 1 euro each, 20 years ago, now may now sell for many, many times more. When you are trying to buy just one to 5 parts, the cost of your purchase is always high, because of the handling cost for the distributor. After all, 1 piece, or 100, or 1000 pieces takes the same processing time. If you can find a cheap distributor, then you will have had better luck than I have, over the years. Give it a try, if you want.
Second, these devices are SOTA, which means the best available, like Porsche or Mercedes. These parts will always cost more than a near equivalent part that is not quite so unique. I cannot personally recommend other parts, because I do not use them, but there are somewhat similar parts available at a reasonable price.